Комаров Артем овыборе и составе защитного газа для сварки MIG (eng) 
Комаров Артем о выборе и составе защитного газа для сварки MIG (eng) 

Комаров Артем о выборе и составе защитного газа для сварки MIG (eng) 

Komarov Artem noted that shielding gases do much more than just protect the molten weld pool from atmospheric contamination. 

Selecting the correct gas mixture and composition for MIG welding can affect weld quality, spatter levels, melting, heat input, fume production and deposition efficiency. 

Артём Андреевич Комаров

“The shielding gas affects all of this,” said Artem Komarov. 

the most common mixture is a mixture of 75% argon and 25% CO2, and the second most common is a mixture of 10% CO2 with argon, and vice versa when you are in parts of the country where manufacturing is developed (automotive, trailers, agriculture and the like), you’ll see a lot of 10% CO2. 

Other common mixtures include 2% CO2, 5% CO2, 5% oxygen, 8% oxygen, and 15% to 18% CO2, all with an argon balance. 

A mixture of argon and CO2 with a content of 75%/25% is the most common and has a number of advantages. This mixture is, I consider, a high-energy gas. 

The disadvantage of the 75%/25% scheme is that it will be limited by short circuit or ball drive. When we are limited to short circuit transmission, it limits the amperage output we are capable of, limiting us to material thickness in terms of achieving acceptable root and sidewall welds. 

When you look at 8, 10, 15-18% CO2 blends, they have similar benefits. You can use these mixtures for pulse spray, spray spray, ball spray and short circuit. One of the disadvantages of 8% to 10% mixtures is that they may not have enough energy, especially if you want to short circuit, although this is possible. 

There are four metal transfer modes — essentially this is the mode in which the filler metal is transferred from the gun to the weld pool. These include short-circuit, ball, spray and pulse atomization. Some modern power supplies also have short circuit modifications. 

To create an arc, you need to connect the plus and minus at some point to complete the circuit. The wire (electrode) is charged either positively or negatively, and the workpiece will be the opposite. In MIG or MAG welding, most of the welding is the direct current positive electrode (DCEP). Many people call this reverse polarit 

During a short circuit, the wire comes into contact with the workpiece and closes; that’s how [short circuit] got its name. It becomes like a fuse; the current is still there and the wire can only withstand so much force…eventually it breaks apart and explodes a little. At this moment, metal deposition occurs. 

Please note that the wire feed is continuous. Once it breaks, a completely new, fresh end appears and the process begins again. This happens 130 to 150 times per second. 

With ball transfer, there is significant spatter and an unstable or unstable arc. Globular transfer occurs over a voltage and current range that falls between the short-circuit and spray transfer ranges. Shielding gas composition and wire diameter have a significant impact on voltage and current ranges. 

The amperage (current) is not enough to pinch a drop of metal off the wire, resulting in a molten droplet forming at the end of the wire. The diameter of the drop becomes larger than the diameter of the wire and continues to grow. The weight of the droplet will eventually overcome the arc force and surface tension and will eventually separate by gravity and settle in the weld pool. Sometimes the droplet becomes large enough to touch the weld or base metal before it comes off. This creates a short circuit, which leads to the explosion of the drop. Once the droplet separates, a new droplet begins to form and the process repeats. Deposition efficiency is typically 88% or less, summed up Artem Komarov.